An article by Zu Wei Tan
While we often think of sunscreen as an essential product to protect our skin from harmful UV rays, it’s worth considering how it might also affect the tiny ecosystem living on our skin. Could sunscreen be doing more than just preventing sunburn? You might be surprised by what it could mean for your skin!
Our bodies are home to millions of tiny allies called microorganisms. These are especially abundant in our gut and help protect our health. Many people don’t realize that our skin also contains a variety of these microorganisms, making it the second most populated area of our body after the gut. Our skin hosts over a million different bacteria, as well as viruses, fungi, and yeasts. Together, these form what we call the skin microbiota. The balance of these microorganisms can change throughout our lives due to various factors, such as sun exposure.
Getting to Know the Human Skin Microbiota
Not all microorganisms are bad for us. A healthy skin microbiota means there is a good balance between helpful and potentially harmful microbes. When this balance is maintained, our skin acts as a protective barrier, stopping harmful germs from entering our bodies. Our immune system works alongside these skin microbes, protecting against diseases.
Thanks to modern technology, scientists can study the wide variety of microorganisms on our skin without needing to grow them in the lab. Now we know these tiny allies help regulate our immune response and can even assist in fighting off infections.
The Skin Damaging Factor: UV Radiation
Ultraviolet (UV) radiation plays a significant role in skin aging, known as photoaging. When UV rays hit the skin, they can damage skin cells and affect genes, leading to the breakdown of collagen, the protein that keeps skin firm and youthful. UVA rays penetrate deeply into the skin and can indirectly harm DNA, while prolonged exposure to UVB rays weakens the skin’s natural defenses and damages collagen and elastin fibers, resulting in early signs of aging.
How UV Radiation Affects the Skin Microbiota
Research shows that the balance of bacteria on our skin can change when it experiences oxidative stress from UV rays. For example, a type of bacteria called Cyanobacteria tends to thrive during these stressful times. These bacteria can produce important nutrients like vitamins C and E, which are beneficial for our skin’s health. They also create a special compound that absorbs UV light, helping them survive in harsh sunlight.
A similar situation has been observed in individuals with atopic dermatitis (AD). According to a study by Lossius et al. (2021), people with AD often have skin barrier issues and changes in their skin bacteria, with S. aureus being more commonly found than in healthy skin. Treatment with UVB light can alter the microbial population on the skin.
The Importance of Sunscreen
Using sunscreen is essential for maintaining healthy skin. Regular application can reduce signs of aging and improve issues like uneven skin tone and loss of elasticity. Sunscreens fall into two categories: organic, which absorb UV rays, and inorganic, which reflect and scatter them. Common inorganic filters include titanium dioxide and zinc oxide. Beyond preventing sunburn, using sunscreen supports overall skin health.
Inspecting the Evidence that Sunscreen Can Affect the Skin Microbiota
Recent research is shedding light on the effects of sunscreen on the small organisms that inhabit our skin, known as microbiota. It has been found that applying sunscreen can help maintain the balance and health of these microorganisms, especially when we are exposed to the sun’s ultraviolet (UV) rays. Using sunscreen with a sun protection factor (SPF) of 20 can minimize disruptions in our skin’s microbiota.
Interestingly, some sunscreens may promote the growth of certain bacteria that are usually not present on our skin, while others can decrease the numbers of bacteria that thrive in sunny conditions. This indicates that sunscreen may play a role in regulating these bacterial populations, which is important for skin health.
While some studies have explored the direct relationship between sunscreen and skin microbiome, many others are examining specific ingredients within sunscreens. Ingredients like titanium dioxide and zinc oxide, which are commonly used for UV protection, are being studied for their impact on skin bacteria. The use of nanotechnology in cosmetic products is also gaining attention, as it often results in more effective protection against UV rays due to the unique properties of these small particles.
The antibacterial properties of zinc oxide come from its ability to release zinc ions into the environment. The smaller the particles, the more zinc ions are released, which makes them more effective at killing bacteria.
Zinc oxide and Titanium oxide exist in the cosmetic market
It’s worth noting that both titanium dioxide and zinc oxide are allowed in cosmetic products, but their concentrations are regulated to ensure they don’t exceed 25% of the total product. This regulation provides some reassurance that these ingredients are safe for use on the skin. However, there’s still a lot we don’t know about how these chemicals in sunscreen affect our skin’s microbiome.
While protecting your skin from sun damage is essential, it’s also important to think about how sunscreen might influence the health of the microbes living on your skin. As research continues, it’s becoming clear that choosing the right sunscreen is key to ensuring that it not only protects your skin from the sun but also supports the healthy balance of microorganisms on it.
Written by: Zu Wei TAN
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